Cartridge-case base for a sub-caliber projectile

ABSTRACT

Anchoring of a spin-stabilized projectile with a sabot body is provided by grooves arranged on the fin-stabilized projectile, which are engaged by ring-shaped protrusions provided in an axial bore of the sabot body. The distance of the first protrusion from the predetermined breaking points of the sabot body and the height of the protrusions are selected in such a way that the deformation at the predetermined breaking points in case of assembly-related spreading of the segment lies in the resilient range.

FIELD OF THE INVENTION

The invention relates to a sabot for a sub-caliber projectile in theform of a fin-stabilized projectile, having a sabot body in which thefin-stabilized projectile is anchored, and a sabot shell, whichpartially surrounds the front and rear end of the fin-stabilizedprojectile and at least partially the sabot body, wherein the sabot bodyis partitioned into segments by slits, and wherein the slits are limitedby predetermined breaking points at one end of the sabot body.

BACKGROUND OF THE INVENTION

Problems often occur in connection with such sabots, which lie in thedifficulty of providing sealing of the sabot and the sub-caliberprojectile, or respectively fin-stabilized projectile, against thehigh-pressure propulsive gases being generated upon firing.

A sabot in accordance with the preamble is known from EP-A-0 624 774,wherein the, sabot body has an area which is not enclosed by the sabotshell and has a circumferential groove for fastening a shroud. Toovercome the above mentioned sealing problems, longitudinal slits andpredetermined breaking points are provided in the sabot body, whereinthe predetermined breaking points are provided in the area of theinterior diameter at the acceleration portion of the sabot body. In thearea of the circumferential groove, the longitudinal slits have aT-shaped cross section with two shoulders, which are used as additionalsealing faces for the material of the sabot shell located in thelongitudinal slits. The acceleration portion of the sabot body isdesigned to be partially in the shape of a truncated cone with a shellsurface widening toward the front. The sabot shell furthermore has asealing cap, which is designed to work together with the accelerationportion of the sabot body, and a seal.

Further improvements regarding sealing, weight reduction and fragmentformation during firing, as well as a simplified structure, are achievedwith a further development of the above described sabot known fromEP-A-0 855 573. In this case, the sabot body is completely surrounded bythe sabot shell, wherein the sabot shell also partially encloses therear end of the fin-stabilized projectile. The sabot body has the shapeof a hollow cylinder provided with circumferential grooves, whoseexterior diameter is small in comparison with the diameter of the sabotshell.

With the above described sabots, the fin-stabilized projectile isanchored in the form of a screw connection, wherein the threads of thescrew connection must be considered a weak point in regard to sealing.

OBJECT AND SUMMARY OF THE INVENTION

It is therefore an object of the invention to propose a sabot of thetype mentioned at the outset which does not have this disadvantage.

This object is attained by the invention recited in the claims. Here,the anchoring is constituted by grooves arranged on the fin-stabilizedprojectile, which are engaged by ring-shaped protrusions provided in anaxial bore of the sabot body. The distance of the first protrusion fromthe pre-determined breaking points and the height of the protrusions areselected to be such that the deformation at the predetermined breakingpoints in case of an assembly-related spreading lies within a resilientrange. The advantages which are obtained by the invention can be seen inthat sealing is further improved by means of the proposed anchoring. Thedesign of the sabot body proposed by the first embodiment in the form ofa double truncated cone makes possible an improved effect of thepropulsive gases during firing in comparison with the last-mentionedprior art, and a weight saving in comparison with the first-mentionedprior art.

The invention will be explained in greater detail in what follows bymeans of two exemplary embodiment in connection with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view along the line I—I in FIG. 4through the sabot in accordance with the invention with a fin-stabilizedprojectile in a first embodiment,

FIG. 2 is a cross section through the sabot along the line III—III inFIG. 1,

FIG. 3 is a plan view of the sabot in the direction of the arrow A inFIG. 1,

FIG. 4 is a plan view of the sabot in the direction of the arrow B inFIG. 3,

FIG. 5 is a plan view of the sabot in the direction of the arrow C inFIG. 3,

FIG. 6 is a longitudinal sectional view through a sabot body along theline VI—VI in FIG. 7 on an enlarged scale,

FIG. 7 is a plan view of the sabot in the direction of the arrow D inFIG. 6,

FIG. 8 is a longitudinal sectional view along the line VIII—VIII in FIG.9 through the sabot with a fin-stabilized projectile in a secondembodiment,

FIG. 9 is a cross section through the sabot along the line IX—IX in FIG.8,

FIG. 10 is a plan view of the sabot in the direction of the arrow E inFIG. 8, and

FIG. 11 is a plan view of the sabot in the direction of the arrow F inFIG. 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIGS. 1 to 5, a fin-stabilized projectile is identified by 1, and by2 a sabot arranged on the fin-stabilized projectile 1. The sabot 2consists of a sabot shell 3 made of a highly heat-resistant,filler-reinforced thermoplastic material and a sabot body 4 made of alight metal. The sabot body 4 is completely surrounded by the sabotshell 3, wherein the sabot shell 3 engages grooves 5 of the sabot body 4and surrounds a portion of the front and rear end of the fin-stabilizedprojectile 1. The fin-stabilized projectile 1 has grooves 6, which areengaged by ring- shaped protrusions 8 provided in an axial bore 7 of thesabot body 4. The grooves 6 and the ring-shaped protrusions 8 have thesame trapezoidal cross section and engage each other in the manner of adenticulation almost free of play. Further grooves 9 are provided in thefin-stabilized projectile 1 in the area of the front end of the sabotbody 4, by means of which additional sealing is achieved.

In the front part of the sabot shell 3 six conduits 10 are provided,which are evenly distributed on the circumference and taper conicallytoward the rear, and are connected with slits 11, which are alsoconically tapered toward the rear, in the surface of the sabot shell 3.Six segments and six predetermined breaking points 12 are formed by thesix conduits 10 and slits 11, which are locally predetermined by meansof furrows 13 arranged in the conduits 10. Six depressions 14 in theshape of a segment of a sphere and having further furrows 15 areprovided in the rear portion of the sabot shell 3 and form furtherpredetermined breaking points 16.

In a manner not further represented and described, the front end of thefin-stabilized projectile 1 can be covered by a shroud fastened on thesabot shell 3, for which purpose a circumferential groove 17 isprovided. A threaded section 18 is arranged on the rear portion of thefin-stabilized projectile 1, by means of which a stabilizing fin, alsonot represented, can be fastened. A circumferential groove for fixing acartridge case is identified by 19.

In accordance with FIGS. 6 and 7, the sabot body 4 is composed of twotruncated cones of uneven length with a common-sized diameter. Six slits20, which are evenly distributed over the circumference and constitutesix segments, are provided in the sabot body 4 and extend from the rearface 21 to the front end of the sabot body 4, where they are limited bypredetermined breaking points 22. The limiting faces 23 of thepredetermined breaking points 22 are located on an arc of a circle 24,whose center of curvature 25 is located on the center axis 26 of thesabot shell 4. The predetermined breaking points 22 are located in thearea of the smaller diameter of the shorter truncated cone, wherein theshorter truncated cone is oriented toward the front end of thefin-stabilized projectile 1. The distance of the predetermined breakingpoints 22 from the first ring-shaped protrusion 8 and the height of theprotrusions 8 have been selected such that the deformation at thepredetermined breaking points 22 in the course of assembly-relatedspreading of the segments lies in the resilient range.

In FIGS. 8 to 11, a fin-stabilized projectile is identified by 41, andby 42 a sabot arranged on the fin-stabilized projectile 41. The sabot 42consists of a sabot shell 43 made of a highly heat-resistant,filler-reinforced thermoplastic material and a sabot body 44 made of alight metal. The sabot shell 43 surrounds the sabot body 44 with theexception of an area, in which a circumferential groove 45 for fasteningcartridge case is provided, and engages cicumferential grooves 46, 47,48 of the sabot body 44. Moreover, the sabot shell 43 surrounds a largerportion of the front end and a smaller portion of the rear of thefin-stabilized projectile 41. Similar to the way described above bymeans of FIGS. 1 to 5, the fin-stabilized projectile 41 has grooves 6′,which are engaged by protrusions 8′ provided in an axial bore 49 of thesabot body 44. Similar to the way described by means of FIGS. 6 and 7,slits 20′ and predetermined breaking points 22′ are provided on thesabot body 44, wherein the end of the sabot body 44 provided with thepredetermined breaking points 22′ is oriented toward the front end ofthe fin-stabilized projectile 41.

Four recesses 50, evenly distributed on the circumference and having anapproximately V-shaped cross section, and four grooves 51, extending inthe longitudinal direction in axes of symmetry of the recesses 50, bymeans of which predetermined breaking points 52 of the sabot shell 43are locally predetermined, are provided in the front part of the sabotshell 43. A circumferential groove, which is used for fastening ashroud, not represented, is identified by 53. A threaded element 54 isprovided on the back end of the fin-stabilized projectile 41, by meansof which a stabilizing fin, also not represented, can be fastened.

It is also possible to embody the sabot shell 3 and/or the sabot body 4of the first embodiment with three, four or five conduits 10 and slits11, or respectively slits 20, so that costs are saved. On the otherhand, the embodiment with six conduits 10 and slits 11, or respectively20, has less mass and results in fewer separation interferencesfollowing firing. It is also within the scope of the invention to selecta different number and distribution of the recesses 50 and grooves 51,or respectively slits 20′, at the circumference of the sabot shell 43and sabot body 44 of the second embodiment.

In place of a light metal, the sabot body 4 of the first embodiment canalso consist of a highly heat-resistant, filler-reinforcedthermoplastic, in particular fiber-reinforced, material.

What is claimed is:
 1. A sub-caliber projectile with sabot, in the formof a fin-stabilized projectile, comprising a sabot body in which thefin-stabilized projectile is anchored, a sabot shell, which partiallysurrounds the front and rear end of the fin-stabilized projectile and atleast partially the sabot body, wherein the sabot body is partitionedinto segments by slits, and wherein the slits are limited bypredetermined breaking points at one end of the sabot body, wherein theanchoring is constituted by grooves arranged on the fin-stabilizedprojectile, which are engaged by ring-shaped protrusions provided in anaxial bore of the sabot body, wherein the distance of a first of saidprotrusions from the predetermined breaking points and the height ofsaid protrusions are selected in such a way that deformation at thepredetermined breaking points in case of assembly-related spreading ofthe segments lies in the resilient range.
 2. The sub-caliber projectilewith sabot in accordance with claim 1, wherein the grooves arranged onthe fin-stabilized projectile have a first trapezoidal cross section andthe ring-shaped protrusions provided in the axial bore of the sabot bodyhave a second trapezoidal cross section and engage each other almostfree of play wherein the first trapezoidal cross section and the secondtrapezoidal cross section are the same.
 3. The sub-caliber projectilewith sabot in accordance with claim 1, wherein the sabot body iscompletely surrounded by the sabot shell, wherein the sabot body iscomposed of two truncated cones having the same size larger conediameter, wherein one of the two truncated cones is shorter than theother truncated cone, and the predetermined breaking points are arrangedin the area of the smaller cone diameter on the shorter truncated cone.4. The sub-caliber projectile with sabot in accordance with claim 3,wherein the shorter truncated cone of the sabot body having thepredetermined breaking points is orientated toward the front end of thefin-stabilized projectile.
 5. The sub-caliber projectile with sabot inaccordance with claim 3, further comprising a number of conduits in afront portion of the sabot shell which are evenly distributed over thecircumference and conically taper toward the rear, and connected with asurface of the sabot shell via slits, which taper conically toward therear.
 6. The sub-caliber projectile with sabot in accordance with claim5, wherein six conduits and slits are provided in the sabot shell. 7.The sub-caliber projectile with sabot in accordance with claim 5,wherein four conduits and slits are provided in the sabot shell.
 8. Thesub-caliber projectile with sabot in accordance with claim 3, whereinsix slits are provided in the sabot body.
 9. The sub-caliber projectilewith sabot in accordance with claim 3, wherein four slits are providedin the sabot body.
 10. The sub-caliber projectile with sabot inaccordance with claim 3, wherein further grooves are provided in thefin-stabilized projectile in the area of a front end of the sabot body.11. The sub-caliber projectile with sabot in accordance with claim 3,wherein the sabot body consists of a highly heat-resistant,filler-reinforced thermoplastic material.
 12. The sub-caliber projectilewith sabot in accordance with claim 1, wherein the sabot body has anarea not surrounded by the sabot shell, which has a circumferentialgroove for fastening a cartridge case, and the sabot body is arranged onthe fin-stabilized projectile in such a way that an end of the sabotbody with the predetermined breaking points is oriented toward a frontend of the fin-stabilized projectile.
 13. The sub-caliber projectilewith sabot in accordance with claim 12, wherein four recesses, which areevenly distributed at the sabot shell circumference, and four groovesextending in the longitudinal direction, are provided in a front portionof the sabot shell.
 14. The sub-caliber projectile with sabot inaccordance with claim 13, wherein the recesses have an approximatelyV-shaped cross section.
 15. The sub-caliber projectile with sabot inaccordance with claim 13, wherein the grooves are arranged to extend inaxes of symmetry of the recesses.